1. Field of the Invention
The present invention relates to a hydraulic clamp adapted to clamp an object to be clamped (referred to as a clamped object hereinafter) such as a metal mould and the like onto a fixed angular table, for example of a press machine and an injection moulding machine, and more specifically to a hydraulic clamp of the type including a clamping member adapted to be actuated for clamping along an axis declining in a forward direction relative to the clamped object.
2. Description of the Related Arts
Such a known hydraulic clamp is disclosed in Japanese Patent Laid Open Publication No. 56-163854.
This prior art is constructed as follows as illustrated in a partial view of FIG. 1 of the above-mentioned Publication. In a clamp housing, a guide bore for a clamping member and a cylinder bore of a hydraulic cylinder are formed in series in a backwardly acclivous direction. The clamping member inserted into the guide bore and a piston inserted into the cylinder bore are formed integrally as a one member, and a clamping actuation oil chamber is formed therein behind and above the piston. Accordingly, the clamping member is adapted to be actuated along an axis declining in a forward direction by means of an oil pressure acting on the piston from the oil chamber.
There are, however, following problems associated with the above-mentioned prior art.
Since a peripheral wall and an end wall of the cylinder bore project largely in a backwardly acclivous direction from a peripheral wall of the guide bore, a height of the hydraulic clamp becomes high.
When an oil pressure within the oil chamber decreases or vanishes accidentally due to pressurized oil leakage, the clamping member is easily retracted by a disturbing force or a gravitation acting on the clamped object such as a metal mould. Therefore, it is apprehended that accidents such as sudden shifts and droppings of the clamped object from the table would happen.